I'm looking to take a long ride on an old fashion steam train.

What is currently the longest run done by an old fashion steam train
locomotive in the United states today?

virtualprofessor

Great question. I've pulled been to Steamtown USA in Pennsylvania
where they have several active locomotives, but they only run them
very short distances. All steam trains currently active in the USA are
"preserved steam" run for the tourist trade. A list of all of the
active steam runs of any significance in the USA can be found at the
Steam Trains Today site:

http://pages.zoom.co.uk/usabyrail/html/us_steam_trains.htm

According to "Steam Trains Today", the longest active train is Cumbres
& Toltec

"The longest and highest narrow gauge steam railway in America,
crossing the continental divide at Cumbres Pass then snaking through
the Toltec Gorge of the Los Pinos River before making a precipitous
descent towards Chama, New Mexico. The Colorado Limited travels from
Antonito to Osier, Colorado, through Toltec Gorge. The New Mexico
Express leaves Chama, New Mexico, for Osier via Cumbres Pass. You can
make through trips either way between Chama and Antonito, returning by
road. Contact PO Box 668, Antonito, CO 81120 and PO Box 789, Chama, NM
87520.   Tel Colorado Limited 719 376 5483 or New Mexico Express 505
756 2151."

Although it specifies "narrow gauge", I looked at the lengths of all
the other train routes, and it really is the longest.

The Official Cumbres & Toltec Scenic Railroad Web Site is found at:

http://www.cumbrestoltec.com/

Unfortunately, they have delayed the opening of their season due to
wildfire hazards in the West.

If you're looking for something on the East Coast, the Cass Scenic
Railroad in West Virginia looks like the longest. The Cass website,
complete with maps, schedules and pricing is found at:

http://www.cassrailroad.com/schedule.html

If you want to look at some local steam locomotives for a warm-up,
there's you can find a list of all the surviving steam locomotives in
North America at:

http://www.steamlocomotive.com/lists/

If you decide to leave the USA on your quest, there are some actual
operating steam railroads in different countries, which you can find
on John Raby's page at:

http://www.geocities.com/john_raby/active.html

Google Search terms used:

longest steam railroad in USA
world steam railroads

I hope you have a great vacation :-)

It's not a regular service, but I ran across this special run from
Seattle to Yellowstone and back:
http://www.alkitours.com/montana.html

The Cumbres & Toltec ride really is excellent.  I took the trip back
in 1978 or so, and it is an all day expidition.  There is no climate
control - we went in June or July and froze our...  well, lets say we
were darn cold.  :-)

It is a must see for any train enthusiast.  If you are in the area,
you may also want to head North a bit and visit Alpine Tunnel, the
highest rail tunnel in the US.  Closed now, because of a cave in, but
still a pretty magnificent site.

virtualprofessor-

Here are two that I am personally familiar with.  

The Tarantula (Fort Worth, TX): 21 mile run between Fort Worth
Stockyards and Grapevine, TX.

http://www.tarantulatrain.com/


The Texas State Railroad (Rusk, TX): 25 mile run between Rusk, TX and
Palestine, TX.

http://www.texasstaterailroad.com/

Enjoy!

kenmkuhl